EP0158963B1

EP0158963B1 - Multicolour inked ribbon cartridge and related positioning mechanism for an impact serial printer

Info

Publication number: EP0158963B1
Application number: EP85104301A
Authority: EP
Inventors: Cosimo Cassiano; Fabio Pessina
Original assignee: Bull HN Information Systems Italia SpA
Current assignee: Bull HN Information Systems Italia SpA
Priority date: 1984-04-16
Filing date: 1985-04-09
Publication date: 1990-03-21
Anticipated expiration: 2005-04-09
Also published as: KR850007416A; DE3576670D1; IT8420554A1; JPS613775A; US4650355A; KR930007624B1; EP0158963A3; IT8420554A0; JPH0584230B2; CA1233426A; EP0158963A2; IT1176062B

Description

The present invention relates to a multicolour inked ribbon cartridge and to a positioning mechanism of such cartridge in an impact serial printer.
An impact serial printer generally consists of a platen, a carriage moving parallely to the platen and a printing head (for instance of the needle type) mounted on the carriage and sequentially actuated during the carriage movement to generate a printed character row on a printing support arranged against the platen.
The character printing support is obtained thanks to an inked ribbon, typically black, arranged between such support and the printing head. The need of more and more users to obtain a multicolour printing induced, in the last years, the impact printer manufacturers to study simple and unexpensive optional mechanism which, mounted on a conventional solid colour printer frame, change it in a multicolour printer.
This change is essentially enabled by the use of an inked ribbon cartridge where the ribbon is constituted by a plurality of longitudinal contiguous bands of different colour and by providing the printer with additional mechanisms able to position such cartridge in order that the desired ribbon band is positioned between the printing head and the printing support.
The most of the multicolour inked ribbon cartridges have a structure generally similar, apart from the height, to the ones of the solid colour inked ribbon cartridges, and, like these last ones, are supported by the printing carriage.
Though, in the case of a multicolour printer, the carriage is provided with a cartridge housing plateform, such plateform being able to cover a plurality of positions as to the printing head equal to the number of the multicolour ribbon bands.
In this way the positioning of a determined band of the multicolour ribbon, between the platen and the printing head is obtained by suitably tilting the plateform (and therefore the whole cartridge) as to the printing head.
This tilting can be performed at the end/begin of a row serial printing process or during the printing process itself.
In the first case the plateform is provided with mechanisms of mechanical type (spring, articulated arms, pawls) which interacts with suitable cams arranged at the end/begin of the printing run, as for instance disclosed by US Patents No. 4,280,767 and 4,368,993.
Solutions of such kind greatly limits the printing speed as they compel the printing head to perform one full pass for each required colour, in order to print a character row.
In the second case such inconvenience is overcome since the mechanical devices enabling the relative shift of the housing plateform of the multicolour inked ribbon cartridge as to the printing head are controlled by electromechanical actuators.
In this case several multicolour inked ribbon bands can be selectively interposed between printing head and printing support during execution of the serial printing process.
The electromechanical actuators can be mounted directly on the printing carriage, as for instance disclosed in US Patent 4,407,595.
Alternatively, in order not to make the carriage heavy and therefore increase its inertia, such mechanical actuators can be suitably restrained to the printer frame, as for instance disclosed in US Patent n. 4,391,540.
The most of the positioning mechanism of the multicolour inked band contained in a cartridge mounted on the printing carriage (examples of such mechanisms are disclosed by the above mentioned US patents) have a high number of mechanical components which, besides being expensive, do not allow their easy assembly and their subsequent mounting on a solid colour serial printing frame.
Further, the solutions involving the mounting of the multicolour inked ribbon cartridges on the carriage are affected by a basic limitation. In fact, owing to the small size of the cartridge, the multicolour inked ribbon contained therein is not long enough as to provide an adequate useful life of such cartridge.
With black ribbon cartridges this problem is not particularly felt because the excellent chemical-physical characteristics of such ink assure for these cartridges a performance of several millions of printed characters.
The performances of a ribbon imbued with a coloured ink different from the black one, for instance yellow, are however very low owing to the different chemical-physical characteristics of the ink.
A multicolour serial printer therefore needs of multicolour inked ribbon longer than the one normally used for a solid-colour printer and therefore of a corresponding more voluminous cartridge.
This need, together with the one to relieve the carriage of all the mechanical parts devoted to the positioning of the multicolour ribbon has recently induced some manufacturers of serial printers to use multicolour inked ribbon cartridges of greater size which are housed on suitable plateform mounted on the printer frame, these plateforms, like the ones mounted on the printing carriage, being able to perform a relative shift as to the printing head.
However, in this case the inconvenience is still present of a relatively high number of mechanical components constituting the positioning mechanism of the multicolour ribbon and of a consequent difficulty in manufacturing such components on the frame of a solid-colour serial printer.
Further, contrarily to the Cartridges mounted on the printing carriage and transversely moving with it, so that the ribbon portion interposing between printing head and printing support is minimum, the use of transversally fixed cartridges causes the interposed ribbon to be freely interposed between printing head and printing support for the whole length of the platen.
The consequence is that the plateform itself must be provided with additional means tensioning and guiding the interposed ribbon portion to avoid detrimental vibrations of such portion between printing head and printing support during the printing process and to assure that such ribbon portion follow immediately and correctly the movements of the cartridge housing plateform.
Particularly, it is essential that the inked ribbon is correctly positioned in correspondence of the variable position along the printing line where the printing head is placed each time.
It is known from conventional typewriters that a ribbon guide may be used for positioning a multicolour (red/black) ribbon at a printing location and for lowering the ribbon in order to provide print visibility once a character has been printed.
To prevent finger soiling when handling the ribbon it has been further proposed in US-A-2,386,439 to provide the ink ribbon for a typewriter with a ribbon guide which can be removably fixed to a ribbon carrier of the typewriter, but which is still operated by conventional mechanisms for raising and lowering it on demand, in order to properly locate the desired colour band at the printing location.
A different approach is followed in FR-A-2,306,836 where an ink ribbon cartridge is used. The cartridge has two arms extending up to the printing location and is rockably mounted on the typewriter frame so as to properly locate the desired colour band at the printing location. In this case a ribbon guide is not required, the ribbon positioning being performed by the cartridge itself, which may be rocked by very simple mechanisms.
This kind of cartridge may be used in serial printers, in which case the cartridge must be mounted on the printing carriage for reciprocation along the whole printing line.
The same cartridge is unsuitable for properly locating the ink ribbon at a printing location in case the cartridge is modified for mounting on the printer frame, the two arms extending up to the beginning and the end of the printing arm respectively.
In this case a ribbon guide, which follows the carriage movement is required and involves the use of positioning mechanism for the ribbon guide, which are mounted on the printing carriage or extends along the printing line and at the same time cooperate with the printing carriage for positioning the ribbon guide and a printing location variable along the printing line.
Thus even if means are provided for rocking the cartridge additional means are needed for positioning the ribbon guide- These additional means make the positioning mechanism of the multicolour ribbon furtherly complicated.
This invention overcomes the above mentioned inconvenients and greatly simplify, as far as both the structure and the assembling, the devices which, when mounted on a printer of conventional type, change it in a multicolour printer.
According to the invention this is obtained by using the cartridge itself as a positioning mechanism for the multicolour ribbon without need of additional mechanisms other than those required to position the cartridge itself.
In other words the cartridge of the present invention is an integral and active part of the positioning mechanism.
According to a first aspect of the invention the cartridge, of a fixed type, that is to be mounted on the printer frame instead of the printing carriage, is constituted by a housing body for the multicolour ribbon and by two arms protruding from such body, said arms being provided with suitable openings allowing the passage of the ribbon which, owing to feeding devices internal to the cartridge, gets out from an arm and into the other one during the printing process.
The cartridge body has two lateral cylindrical- shaped projections which insert into two suitable housings of the printer frame sides. Though, when assembled, the cartridge is able to pivot around the axis defined by its two projections, said axis being parallel to the platen and the ribbon portion extending between the two arms and intended to be interposed between printing head and printing support for the whole length of the platen.
The cartridge controlled rotation, and therefore the positioning of a suitable multicolour ribbon band between printing head and printing support, is assured by a cam actuated by a motor (for instance a step motor) such arm interacting with the cartridge body.
It is therefore clear that in the case of the present invention the cartridge body itself performs the functions carried out in the prior art, by the housing plateform of the cartridge.
According to a further aspect of the invention the cartridge is provided with a string tight between the ends of the two arms upon the multicolour portion interposing between printing head and printing support.
Such string is used to hook therein, freely slidable along the string, a positioning and guiding element of the ribbon which therefore tends to follow the cartridge tilting.
The ribbon positioning and guiding element is further hitched to the carriage and follows it in its transversal movement in order to assure the correct positioning and tension of the multicolour ribbon zones contacted by the printing head during its transversal moving.
These and other characteristics will appear clearer from the following description of a preferred embodiment of the invention and from the enclosed drawings where:

Figure 1 schematically shows in perspective view the structure of a serial printer where a multicolour ribbon cartridge and the related positioning mechanism of the present invention are mounted.
Figure 2 schematically shows in side view the multicolour ribbon cartridge and the related positioning mechanism of the present invention.
Figure 3 shows in perspective view the element which assures the local positioning and tension of the multicolour ribbon, and which is part of the multicolour ink ribbon cartridge of the present invention.

With reference to Fig. 1, the printer comprises a frame constituted by a baseplate 1 and two side plates 2, 3.
Between sides 2, 3 a platen 4 and two parallel bars 5, 6 are restrained. A carriage 7 can move along bars 5, 6. A printing head 8, for instance of the needle type well known in the art and disclosed for instance by US Patent n. 4,260,270, is mounted on carriage 7.
The mechanisms assuring the transversal moving of carriage 7 are not shown in Fig. 1 both because such mechanisms are not essential for the invention understanding and because they are well known in the art and for instance disclosed by european patent application published on Nov. 17, 1982 with n. 64626.
Carriage 7 is provided with two vertical pins 9, 10 arranged on the sides of printing head nose 8A. The function of such pins will be explained later on.
Sides 2,3 of the frame have two housings 11,12 respectively, for insertion of two corresponding cylindrical shaped projections 13, 14, protruding outside the body of a multicolour cartridge 15.
Cartridge 15 is provided with two arms 16, 17 of suitable length and arranged with suitable openings at their ends to enable the passage of ribbon 8 for instance constituted by 4 longitudinal contiguous bands of different colours.
In the case of the described embodiment, projections 13, 14 axis does not intersect the bary- center of cartridge 15 so that once this last is mounted on the printer frame it tends to rotate around such axis, owing to its weight, in the direction which tends to lower the portion of ribbon 18 interposed between printing head 8 and platen 4 towards basis 1.
Two hooks 19, 20 hinged on sides 2, 3 allow to restrain to these sides the cylindrical shaped projections 13, 14, preventing their removal from corresponding seats without hampering the cartridge freedom to rotate around the axis of these projections.
Each hook is kept in closed position by a spring, such as spring 22 of fig. 1.
Angular position of cartridge 15, when mounted on the printer frame, is determined by its arm 17 resting on a cam 23.
Such cam is splined to shaft 24 of a step motor 25 which is suitably mounted on side 3.
It is clear that by suitably rotating cam 23 cartridge 15 can be inclined as to the printer plane in order that a prefixed band of the multicolour ribbon 18 interposes between end 8A of printer head 8 and platen 4.
The interaction between cam 23 and cartridge 15 is evidenced in fig. 2 where the cartridge and the related positioning mechanism of the present invention is schematically shown in side view.
A paper printing support 4A laying against platen 4 is also shown in fig. 2.
Referring again to fig. 1, inside the cartridge body a feeding roller (not shown) and a leaf spring (not shown) suitably pressing against such roller assure the advancement of ribbon 18 getting out from arm 17 to go into arm 16.
The feeding roller can be manually operated by a knurled knob 28 or, once the cartridge is mounted on the printer, by an elastical joint 29 engaging with the feeding roller axis.
A motor 30 assures the rotation of joint 29.
A suitable tension of ribbon 18 between two arms 16, 17 is generally assured by an additional leaf spring (not shown too) internal to arm 17.
A detailed description is omitted of the feeding and tension mechanisms of ribbon 18 internal to cartridge 15, which are well known in the art.
An example of such mechanisms is for instance disclosed by English patent n. 1,502,760.
A detailed description of elastical joint 29 is omitted too as it is well known in the art too.
An embodiment example of such joint can be found for instance in English patent 1,522,203.
A string 21, for instance in the elastic material known with the trade mark name "Nylon", is tight between arms 16 and 17 of cartridge 15, upon ribbon 18.
A positioning and tensioning element 31 of ribbon_18, which is schematically shown in fig. 1, is hooked to this string.
Element 31, in plastic material, can freely slide along string 21 axis but it is compelled to follow the shifts of such axis as imposed by the cartridge tilting around rotation pivots 13, 14.
Fig. 1 shows that element 31 comprises two hollowed pins 32, 33 which engage on pins 9, 10 respectively when the cartridge is mounted on the printer.
Therefore element 31 slides both parallely to the printing line when fed by printing carriage, and perpendicularly to this line owing to the tilting of cartridge 15 and therefore of string 21.
Fig. 3 is a more detailed perspective view of local positioning and tensioning plastic element 31 which is obtained for instance by molding.
Further to hollow pins 32, 33, receiving pins 9, 10 respectively, element 31 comprises some additional hollow pins 34, 35, 36, 37.
Such additional pins define a path for ribbon 18 and prevent possible vibrations of such ribbon during the printing process to propagate to the ribbon portion between additional pins 34, 37 causing a bad printing quality.
It is to be noted that such portion is always interposed between end 8A of printing head 8 and printing support 4A of fig. 2 as both printing head 8 and element 31 transversally move with printing carriage 7 of fig. 1.
The relative position of the several pins is assured by a cap 38 to which one end of such pins is restrained.
Some shoulders 39, 40 joining cap 38 to the external surface of pins 33, 32 respectively, provide the required stiffness to the element. Cap 38 is provided, on the top, with a pair of opposed teeth 41, 42 arranged to constitute a hook with flat eye which is hitched to string 21.
Two retaining elements 43, 44 provided with a pair of fingers forced into the hollows of pins 36, 37 and 34, 35 encage the ribbon and constrain it to follow the movement imposed by element 31 also when such movement is perpendicular to the printing line.
It is clear that several changes may be brought to the disclosed multicolour ribbon cartridge and to the related positioning mechanism without departing from the scope of the present invention.
For instance the cartridge can be forced to lay with its arm 17 on cam 23 by means of suitable elastical means (for instance a leaf spring) mounted on the printer frame and interacting with the cartridge body.

Claims

1. Multicolour inked ribbon cartridge for impact serial printer of the kind where a printing head (8) mounted on a carriage (7) slides parallely to a platen (4) for subsequently printing a character row along a printing line on a printing support leaned against said platen, comprising:

a housing body (15) comprising a multicolour ribbon (18) formed by a plurality of longitudinal contiguous bands of different colour, said body (15) being provided with two parallel arms (16,17), a portion of said multicolour ribbon extending between the ends of said arms outside said body, said portion of ribbon being intended to interpose between said printing head and said printing support along the whole printing line, and said cartridge being mounted on the frame of said printer for rotation along an axis parallel to the printing line, so as to interpose between said printing head and said printing support a selected colour band of said ribbon, characterized by that it comprises:

guiding means (21) fixed to and extending between the ends of said two arms (16, 17)

a positioning and tensioning element (31) slidably mounted on said guiding means (21) and having encaging elements (36, 37, 34, 35, 43, 44) forming openings where the ribbon is slidably threaded, and means (32, 33) for mounting said tensioning element (31) to said carriage slidable in a direction perpendicular to said printing line and parallel to said platen, so that said positioning and tensioning element (31) moves along said printing line with said carriage, and that the angular displacement of said arms due to said rotation of the cartridge is transmitted through said guiding means (21) to said positioning and tensioning element (31) whereby inserting a selected coloured ribbon band between said platen and said printing head.

2. Multicolour inked ribbon cartridge as per claim 3, further characterised by that said guiding means are constituted by a string upperly tight between and fixed to the end of said two arms.